Schools, adult care facilities, penal institutions, and other entities that deal in significant population management encounter enormous difficulty observing health and physical characteristics of individuals under their supervision. Illness and injury are persistent threats to the general health and safety of groups of individuals when they spend substantial time in close proximity. Detecting illnesses or injury early can be difficult in the initial phases, particularly for children who may not recognize their own symptoms. The longer a sick individual remains in the population, the greater the risk of infecting others.